The present invention relates to a coupler plug, in particular for a planar lambda probe, made up of a housing, namely a base element and a cover element, as well as electrical components, that may be inserted and fixed in the housing, and an adjusting element for a probe, such as, for example, a planar broadband lambda probe, which is mounted in the coupler plug or outside the coupler plug via a further contact element, the cover element being attachable over the adjusting element and having a primary locking mechanism (first latching position) and a secondary locking mechanism (final position) cooperating with the cover element.
Coupler plugs of the aforementioned type may be configured for the connection between a cable harness plug and a lambda probe, the connections in the coupler plug being provided for adjustment, signal, and/or heating of the probe. The lambda probe and the lambda control, in connection with three-way catalytic converters, may represent an effective method for cleaning exhaust emissions. The lambda probe, which, for example, may be inserted into an exhaust system, may include a sensor for determining the oxygen content in the exhaust gas.
The residual oxygen content may be well-suited for use as a measured quantity, and it may regulate the air-fuel ratio, because it may indicate precisely whether the air-fuel mixture is being completely combusted.
In this context, the lambda probe may supply a voltage signal, which represents the momentary value of the mixture composition and which may follow the mixture changes. The fuel supply to the engine may be controlled by a carburation system in accordance with the signal from the lambda probe so that a stoichiometric air-fuel ratio xcex=1 is achieved. Heated or unheated probes may be used in accordance with the configuration of the exhaust gas system and the conditions in which they are used. Outside the field of motor vehicles, other applications of the lambda probe may include, e.g., regulating gas motors or oil/gas burners.
In particular, broadband lambda probes may be configured in modular form and, in combination with planar technology, may facilitate the integration of a plurality of functions. They may have functional layers, which are made up of a porous protective layer, an external electrode, a sensor film, an internal electrode, a reference gas channel film, an insulation layer, a heating element, a heating film, a resistor or adjusting element, and connection contacts.
Because broadband lambda probes may be made up of the combination of a nernet concentration cell (=sensor cell) and a pump cell that transports oxygen ions, it may measure very precisely, not only in the stoichiometric point at xcex=1, but also in the lean and rich mixture ranges.
Every probe may be required to be individually adjusted. For this purpose, the probe may have a built-in resistor (xe2x80x9cmini-hybridxe2x80x9d). The adjustment, which may be performed using a laser beam, may be made by properly ablating the resistance layer made up of a ceramic substrate, thereby inducing a change in the resistance, so that an adjustment follows.
One exemplary embodiment may provide for the adjustment unit, i.e., the resistor, to be mounted directly at the probe. A further exemplary embodiment may provide for the resistor to be accommodated externally, for example, on a cable harness plug that is coupled to the probe.
Heretofore, the adjustment may have been performed by transporting the housing of the coupler plug, in which the resistor is embedded, to the adjustment station without the cover element. After the appropriate laser processing for the adjustment, the cover element was mounted at a further assembly station.
To prevent the ingress of humidity, contamination or the like into the coupler plug, and to assure that the appropriate atmosphere prevails within the coupler plug, the cover element may have additional seals. Furthermore, pressure equalizer elements may be mounted on the housing of the coupler plug.
However, the seals may accomplish their sealing function only if the cover element is latched in its final position (secondary locking mechanism). When the coupler plug is transported to the adjusting station, either the cover element is completely removed, or it rests on the housing of the coupler plug, thus not accomplishing any latching function with the housing, because the cover element may be required once again to be removed in order to adjust the adjusting element. Therefore, a danger may exist, such as, for example, when the coupler plug is being transported, that dust, dirt, or humidity may penetrate into the housing, thereby impairing the functioning of the coupler plug.
The present invention may refine an embodiment of the coupler plug, such as, for example, a planar broadband lambda probe, so that the probe may be manufactured in a cost-effective manner, and, as a result of the refinement, undesired features of the related art may be avoided.
A seal may be provided on the cover element, the seal having sealing lips pointing away from the cover element, the sealing lips, in the first latching position of the cover element, bringing about a sealing connection with the housing.
The coupler plug may be configured to be of small construction, because, due to the compact configuration, i.e., the insertion of electrical contacts into a base element and the placement of the adjusting element likewise in the coupler plug, the exterior dimensions of the coupler plug, which may be positioned between a cable harness and a lambda probe, may be small.
In addition, an exemplary coupler plug according to the present invention may have only a small number of components. As a result, a cost-effective and efficient manufacturing process may be provided.
Because the base element is completely enclosed by the cover element, the interior of the coupler plug may be sealed off by configuring the sealing lips within the cover element, thereby protecting it, for example, from dust, dirt, or water spray, even in the first latching position of the cover element.
In addition, this may also support the latching of the cover element to the base element. A first and a second latching mechanism, i.e., a primary and secondary locking mechanism, may be provided. The latter may be configured such that the cover element has latching arms, which, in the closed state of the cover, contact the base element of the coupler plug and produce a latching there using detents. In the first latching position, the sealing lips mounted on the circumferential seal on the cover element already engage in cutouts on the sides of the housing and therefore may provide protection at least against dust and dirt. By once again pressing the cover element in the direction of the housing, the circumferential seal that is mounted in the cover element may become functional when the final position (the secondary locking mechanism) is reached, and it may completely seal the housing from its external environment. The seal may be configured so that the housing is watertight in the final position of the cover element. In this final position, the sealing lips may cease functioning and may all but completely accommodated in the cutout in the housing.
The aforementioned seal may be injection-molded on the cover element, so that it is non-detachably mounted.
The cover element may be made of PBT (polybutylene terephthalt) or a similar material.